I have a set of old M/T valve covers. Like the ones in the picture. I would like to get rid of the fins and M/T, and smooth them out to match the raised "inscription pad" at the bottom, for a custom look. I had thought about having them machined down but that would go into the recess underneath the raised pad.

Is there something I can fill in the area between the fins with? Too deep to want to use normal body filler obviously. I found "Metal Fill" supposedly cures hard enough to drill and tap, Bondo also has a metal filler. I am just wondering if whatever polymer base is in them will stand up to the heat that valve covers will being seeing on a street driven car.

Thanks all.

I know that if you use All Metal they say you can powdercoat over it if you use extra hardner in it so it should hold up to the heat.

THis is what we used to use the the Navy for repair aluminum castings regardless.

http://www.devcon.com/products/products.cfm?brand=Devcon&family=Aluminum%20Putty%20%28F%29

Does NOT look like aluminum when cured and it will not polish out. Dunno if you can powder coat over it either.

According to the MSDS information "Heating resin above 300 F in the presence of air may cause slow oxidative decomposition." so it may not be best.

Mill the fins off and weld the holes

I'd just sell them and buy a set that are smooth.

This has been done for SB, just not 100% sure about the make of covers. IIRC the finned MP covers can be milled down for a smooth look.
Again IIRC member LAR414 had milled ali covers which thus looked somewhat stock once painted. My memory could be wrong on the specifics (though not the fact it has been successfully done with the right covers) but FWIW......